This invention relates to progressing cavity pumps and, in particular, a progressing cavity pump moveable through production tubing in a well and insertable through the tubing string into a set position downhole.
A progressing cavity pump is a well known pump, frequently called a xe2x80x9cMoineauxe2x80x9d pump, that has an elastomeric outer element or stator has a helical inner surface. A metal rotor having a helical exterior inserts within the stator.
Progressing cavity pumps of this type are used for many purposes, particularly for pumping viscous liquids. These pumps are also used as oil well pumps. When used as an oil well pump, the stator is secured to the lower end of the well tubing and lowered into the casing of the well with the well tubing. The rotor is secured to the lower end of the sucker rod and lowered through the tubing to a position inside the stator. The sucker rod is rotated by means of a rotary power source at the surface. U.S. Pat. No 2,267,459 shows one type of installation for an oil pump.
One disadvantage is that if the stator needs to be serviced, the string of tubing must be pulled. This is time consuming and requires special equipment. U.S. Pat. No. 3,347,169 shows a insertable progressing cavity pump wherein the stator is lowered through the tubing on a flexible drive cable and secured by a seat.
U.S. Pat. No. 4,592,427 shows an insertable progressing cavity pump that is lowered through the tubing on sucker rods and secured by a seating nipple and torque reactor cup arrangement.
The progressing cavity pump of the present invention is lowered through the production tubing on a rod string. The pump is releasably latched down hole and held against rotation.
In accordance with a broad aspect of the invention, there is provided in an insertable progressing cavity pump, the pump being insertable in a bore of a tubing string by carriage on a drive string, the insertable progressing cavity pump comprising: a stator, a helical rotor locatable in the stator and including a coupling for connection to the drive string, a tubular housing for accommodating the stator therein and sized to be insertable into the tubing string, a pump hold-down arrangement in communication with the housing and disposed above the stator for engaging the pump into the tubing string, and a torque transmitting arrangement acting between the rotor and the housing to transmit torque from the rotor to the housing in both the clockwise and counter-clockwise direction, when the housing is carried on the drive string.
The torque transmitting arrangement can act directly or indirectly between the rotor and housing. In one embodiment, the torque transmitting arrangement includes a portion on the coupling and a portion on the housing.
The pump can include a collar on the housing and an enlarged sub on the coupling that are formed to cooperate to permit the pump to be carried on the drive string. In one embodiment, the torque transmitting arrangement is formed above the enlarged sub on the coupling and is selected to engage with an aperture that extends through the collar.
The torque transmitting arrangement acting between the rotor and the housing can be a portion on the housing that can engage with a portion on or in communication with the rotor such as a sub. As an example, the torque transmitting arrangement can be corresponding faceted arrangements such as hexagonal, square or rectangular openings/subs, corresponding oval openings/subs or frictionally interlocking arrangements such as vertically knurled components.
In another aspect of the invention, there is provided an insertable progressing cavity pump installation for use in a tubing string in a wellbore, the insertable progressing cavity pump installation comprising: a tubing string insert connectable into the tubing string and having a inner bore defined by an inner wall and pump hold down arrangement formed on the inner wall and an insertable progressing cavity pump insertable through the tubing string by carriage on a rod string, the pump including a stator, a helical rotor locatable in the stator and including a coupling for connection to the rod string, a tubular housing for accommodating the stator therein and sized to be insertable through the tubing string and an hold down arrangement on the housing disposed above the stator and including an engagement mechanism for engaging with the pump hold down arrangement to releasably secure the pump in the tubing string.
The pump hold down arrangement and the hold down arrangement on the housing can be various corresponding mechanisms or arrangements. As an example, the pump hold down arrangement and the hold down arrangement on the pump can be a corresponding arrangement of a collet and a shoulder, a key and a keyway, or a spring loaded block and a shoulder.
The pump can include a collar on the housing and an enlarged sub on the coupling that are formed to cooperate to permit the pump to be carried on the drive string. In one embodiment, the collar is formed adjacent the hold down arrangement on the housing.
The housing can be formed in various ways. In one embodiment, the housing includes an insert body including a collar for cooperating with an enlarged sub on the coupling to permit the pump to be carried on the drive string and the hold down arrangement on the housing.